Bloom Shortest Path Error Unknown variable n@412

[laurenz]

Hi, we sometimes get this error if we use the bloom shortest path function to find nodes between 2 nodes.

We would really like to know how to fix this issue? We don't understand what is causing this error message.

Resetting the perspective seems to fix it temporarilly, however after using the shortest path function a few times, the error message appears again. After it appears it will always appear when using the shortest path function until resetting the perspective.

Sometimes we also get at first "Expected NO_VALUE to be a path" error in bloom when using the shortest path function between 2 nodes. After that happens we get unkown variable n@412 error on all other nodes with the shortest path function, which had worked before the "Expected NO_VALUE to be a path" error.

[laurenz]

Further info:
Using a Blank Perspective seems to prevent all n@412 errors. The Expected No_Value to be a path error still occurs, but on other nodes the n@412 error does not appear. However, adding categories to the balnk perspective will create n@412 errors again.

[dana_canzano]

any details with reference to
a. Neo4j Version?
b. Bloom Version?

[laurenz]

Hi, yes, sure:
a. Neo4j Version enterprise 4.1.0
b. Bloom Version 1.4.1

[laurenz]

Here is also a debug.log excerpt:
2020-11-23 09:50:35.964+0000 ERROR [o.n.b.r.s.i.ErrorReporter] Client triggered an unexpected error [Neo.DatabaseError.Statement.ExecutionFailed]: Unknown variable n@412., reference 06160dfd-dda4-4914-9ca6-b35b0fc9c92c.
2020-11-23 09:50:35.964+0000 ERROR [o.n.b.r.s.i.ErrorReporter] Client triggered an unexpected error [Neo.DatabaseError.Statement.ExecutionFailed]: Unknown variable n@412., reference 06160dfd-dda4-4914-9ca6-b35b0fc9c92c. Unknown variable n@412.
org.neo4j.fabric.executor.FabricException: Unknown variable n@412.
at org.neo4j.fabric.executor.Exceptions.transform(Exceptions.java:51)
at org.neo4j.fabric.stream.Rx2SyncStream.readRecord(Rx2SyncStream.java:69)
at org.neo4j.fabric.bolt.BoltQueryExecutionImpl$QueryExecutionImpl.request(BoltQueryExecutionImpl.java:179)
at org.neo4j.bolt.runtime.AbstractCypherAdapterStream.handleRecords(AbstractCypherAdapterStream.java:104)
at org.neo4j.bolt.v3.messaging.ResultHandler.onPullRecords(ResultHandler.java:41)
at org.neo4j.bolt.v4.messaging.PullResultConsumer.consume(PullResultConsumer.java:42)
at org.neo4j.bolt.runtime.statemachine.impl.TransactionStateMachine$State.consumeResult(TransactionStateMachine.java:511)
at org.neo4j.bolt.runtime.statemachine.impl.TransactionStateMachine$State$2.streamResult(TransactionStateMachine.java:355)
at org.neo4j.bolt.runtime.statemachine.impl.TransactionStateMachine.streamResult(TransactionStateMachine.java:94)
at org.neo4j.bolt.v4.runtime.InTransactionState.processStreamResultMessage(InTransactionState.java:73)
at org.neo4j.bolt.v4.runtime.AbstractStreamingState.processUnsafe(AbstractStreamingState.java:49)
at org.neo4j.bolt.v4.runtime.InTransactionState.processUnsafe(InTransactionState.java:60)
at org.neo4j.bolt.v3.runtime.FailSafeBoltStateMachineState.process(FailSafeBoltStateMachineState.java:48)
at org.neo4j.bolt.runtime.statemachine.impl.AbstractBoltStateMachine.nextState(AbstractBoltStateMachine.java:143)
at org.neo4j.bolt.runtime.statemachine.impl.AbstractBoltStateMachine.process(AbstractBoltStateMachine.java:91)
at org.neo4j.bolt.messaging.BoltRequestMessageReader.lambda$doRead$1(BoltRequestMessageReader.java:90)
at org.neo4j.bolt.runtime.DefaultBoltConnection.lambda$enqueue$0(DefaultBoltConnection.java:148)
at org.neo4j.bolt.runtime.DefaultBoltConnection.processNextBatchInternal(DefaultBoltConnection.java:237)
at org.neo4j.bolt.runtime.DefaultBoltConnection.processNextBatch(DefaultBoltConnection.java:172)
at org.neo4j.bolt.runtime.DefaultBoltConnection.processNextBatch(DefaultBoltConnection.java:162)
at org.neo4j.bolt.runtime.scheduling.ExecutorBoltScheduler.executeBatch(ExecutorBoltScheduler.java:246)
at org.neo4j.bolt.runtime.scheduling.ExecutorBoltScheduler.lambda$scheduleBatchOrHandleError$3(ExecutorBoltScheduler.java:229)
at java.base/java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1700)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at io.netty.util.concurrent.FastThreadLocalRunnable.run(FastThreadLocalRunnable.java:30)
at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: org.neo4j.graphdb.NotFoundException: Unknown variable n@412.
at org.neo4j.cypher.internal.runtime.pipelined.execution.Morsel$Cursor.$anonfun$getByName$2(Morsel.scala:133)
at scala.Option.getOrElse(Option.scala:189)
at org.neo4j.cypher.internal.runtime.pipelined.execution.Morsel$Cursor.getByName(Morsel.scala:133)
at org.neo4j.codegen.Expression10/0x0000000841baa840.project(Unknown Source)
at org.neo4j.cypher.internal.runtime.slotted.expressions.CompileWrappingProjection.project(CompiledExpressionConverter.scala:160)
at org.neo4j.cypher.internal.runtime.pipelined.operators.ProjectOperator.operate(ProjectOperator.scala:36)
at org.neo4j.cypher.internal.runtime.pipelined.operators.OperatorTask.operateWithProfile(Operator.scala:366)
at org.neo4j.cypher.internal.runtime.pipelined.operators.OperatorTask.operateWithProfile$(Operator.scala:354)
at org.neo4j.cypher.internal.runtime.pipelined.operators.ProjectOperator.operateWithProfile(ProjectOperator.scala:25)
at org.neo4j.cypher.internal.runtime.pipelined.PipelineTask.executeOperators(PipelineTask.scala:68)
at org.neo4j.cypher.internal.runtime.pipelined.PipelineTask.executeWorkUnit(PipelineTask.scala:52)
at org.neo4j.cypher.internal.runtime.pipelined.Worker.executeTask(Worker.scala:135)
at org.neo4j.cypher.internal.runtime.pipelined.Worker.workOnQuery(Worker.scala:91)
at org.neo4j.cypher.internal.runtime.pipelined.execution.CallingThreadExecutingQuery.request(CallingThreadExecutingQuery.scala:41)
at org.neo4j.cypher.internal.PipelinedRuntime$PipelinedRuntimeResult.request(PipelinedRuntime.scala:426)
at org.neo4j.cypher.internal.result.StandardInternalExecutionResult.request(StandardInternalExecutionResult.scala:99)
at org.neo4j.cypher.internal.result.ClosingExecutionResult.request(ClosingExecutionResult.scala:145)
at org.neo4j.fabric.stream.QuerySubject$BasicQuerySubject$1.doRequest(QuerySubject.java:184)
at org.neo4j.fabric.stream.QuerySubject$BasicQuerySubject$1.request(QuerySubject.java:167)
at reactor.core.publisher.FluxPeek$PeekSubscriber.request(FluxPeek.java:130)
at reactor.core.publisher.FluxPeek$PeekSubscriber.request(FluxPeek.java:130)
at reactor.core.publisher.FluxPeek$PeekSubscriber.request(FluxPeek.java:130)
at reactor.core.publisher.FluxPeek$PeekSubscriber.request(FluxPeek.java:130)
at reactor.core.publisher.FluxPeek$PeekSubscriber.request(FluxPeek.java:130)
at reactor.core.publisher.Operators$MultiSubscriptionSubscriber.request(Operators.java:2089)
at reactor.core.publisher.StrictSubscriber.request(StrictSubscriber.java:138)
at org.neo4j.fabric.stream.Rx2SyncStream$RecordSubscriber.request(Rx2SyncStream.java:129)
at org.neo4j.fabric.stream.Rx2SyncStream.maybeRequest(Rx2SyncStream.java:91)
at org.neo4j.fabric.stream.Rx2SyncStream.readRecord(Rx2SyncStream.java:50)
... 25 more

[wedoso]

I meet the same issue here. Any update on it? Do we know the root cause on it now? Currently, my solution is to completely stop the db and close the desktop client.